Recently, the general trends in designing portable electronic devices are toward small size, light weightiness and easy portability. The portable electronic devices such as mobile phones, personal digital assistants (PDAs), digital still cameras, digital video cameras, notebook computers and the like have built-in batteries. If no external power supply apparatus is provided to power the portable electronic device, the built-in battery is usually used as the main power source. If the power supplied from the battery is insufficient, the user may simply plug a power supply apparatus (e.g. a power adapter or a charger) into an AC wall outlet commonly found in most homes or offices so as to receive an AC voltage. The AC voltage is then converted into a DC power to be used for the portable electronic device and/or charge the built-in battery.
Referring to FIG. 1A, a schematic exploded view of a conventional power adapter is illustrated. The power adapter 1 principally comprises a casing member 11, a metallic shielding member 12, an insulating member 13 and a circuit board 14. The casing member 11 includes an upper casing part 111 and a lower casing part 112. The metallic shielding member 12 is used for minimizing the influence of electro-magnetic interference (EMI) and includes an upper shielding part 121 and a lower shielding part 122. For safety, the insulating member 13 is arranged between the circuit board 14 and the metallic shielding member 12 for isolating the circuit board 14 from the metallic shielding member 12. The insulating member 13 is substantially a thin film layer such as an insulating tape. The insulating member 13 is attached onto the inner surfaces of the upper shielding part 121 and the lower shielding part 122 so as to define a receptacle 131 for accommodating the circuit board 14 therein. Some electronic components 141 are mounted on the circuit board 14 for providing power conversion.
FIG. 1B is a schematic cross-sectional view of the circuit board shown in FIG. 1A. Some of the electronic components 141 have respective pins 142 inserting into holes (not shown) of the circuit board 14 from a first surface 143 to a second surface 144. The pins 142 are fixed on the second surface 144 of the circuit board 14 via solder paste 145 such that the electronic components 141 are mounted on the first surface 143 of the circuit board 14. Generally, after the pins 142 penetrates through the holes, the tips of the pins 142 are protruded from the second surface 144 of the circuit board 14 by a specified length.
During the power adapter 1 is subject to a shock test, the circuit board 14 is suffered from vibration in the vertical direction. If the vibration is too strong, the pins 142 protruded from the second surface 144 of the circuit board 14 may pierce though the insulating member 13 and thus the electronic components 141 on the circuit board 14 will be in direct contact with the metallic shielding member 12. Under this circumstance, the power adapter 1 has a malfunction and the product yield is reduced.
Similarly, if the power adapter 1 is suffered from a drop or a strong impact, the pins 142 protruded from the second surface 144 of the circuit board 14 may pierce though the insulating member 13 and thus the electronic components 141 on the circuit board 14 will be in direct contact with the metallic shielding member 12. Under this circumstance, the power adapter 1 has a breakdown and the reliability of the power adapter 1 is reduced.
Therefore, there is a need of providing a cushioning member for use in a circuit board of an electronic device so as to obviate the drawbacks encountered from the prior art.